The present invention relates to a spur-gear mechanism, especially a bevel spur-gear mechanism, having one or more transmission stages.
Gear mechanisms having a bevel gear stage are a generally known structural approach in order, in addition to the important mechanical values of speed and torque, to also alter the spatial position between the drive shaft and the output shaft. The axes of the drive shaft and the output shaft are customarily offset relative to one another by an angle of 90°. Particularly economical is the use of the bevel gear set as the first stage in a generally multi-staged gear mechanism. In particular for drives of conveyor belt units, bevel spur-gear mechanisms enable the parallel alignment of drive and conveyor belt unit.
With a minimal number of individual components, a universal gear mechanism series can be produced that encompasses many structural sizes. The individual components are technically designed in an optimum characteristic curve. Due to the high reproducing frequency of individual components in various variations, this concept additionally has special economical advantages.
There exists for a plurality of comparable gear mechanism series according to the mechanical assembly technique a program that includes not only spur-gear mechanisms but also bevel spur-gear mechanisms. The gear mechanisms are available for all conceivable installation positions and with different types of constructions of the drive and output shafts. Characteristic is the use of an extensively unaltered base housing not only for the spur-gear mechanism but also for the bevel spur-gear mechanism. Alternatively, further auxiliary components, such as block or return lockings and brakes are also available.
Derived from the existing program are product programs that are adapted for special branch strong points and that utilize the advantages of the existing universal structural series, and which at the same time are limited to the assembly of branch-conventional variants. For conveyor belt drives, essentially two-stage and three-stage bevel spur-gear mechanisms are used. For three-stage bevel spur-gear mechanisms, a special variant having a surface of the gear mechanism housing that is enlarged by cooling ribs is also provided.
The drawback of the concept of a universal mechanical assembly gear mechanism is, for branch-specific applications, the prevailing use of identical components. This includes, in particular, the gear mechanism housing. In addition to the mechanical stress, the thermal limiting output is a determinative design criterion for conveyor belt drives. Since in general in surface working or mining, or similar applications, no cooling water is available for the conveyance of loose material, and the use of other cooling and lubricating means, such as oleo or oil/air coolers, is not possible for various reasons, the entire gear mechanism heat must be given off to the air via convection. In addition, the raw environmental conditions that exist at the use site in question, and which have a high occurrence of dust, make the maintenance of the heat withdrawal more difficult, since dust layers that are deposited on the gear mechanism housing have an insulating effect. Known in this connection are bevel spur-gear mechanisms having a housing surface that is enlarged by cooling ribs, and having an axial fan wheel disposed on the drive shaft.
It is an object of the present invention to alter the bevel spur-gear mechanism of the aforementioned general type for use as a conveyor belt drive in such a way that under specific optimization of the housing form, the quantity of heat that is carried off by convection can be permanently increased.